1. Field
The present invention relates to a process for producing a light-emitting semiconductor device.
2. Description of the Related Art
In light-emitting semiconductor devices such as light-emitting diodes and semiconductor lasers, light-emitting elements are usually covered with an encapsulating material for the purposes of protection and color alteration. A white-light-emitting semiconductor device is constituted of a blue-light-emitting element and an encapsulating material formed so as to cover the element and containing a yellow fluorescent substance. For forming this encapsulating material in such white-light-emitting semiconductor devices, epoxy resins have hitherto been generally used (see, JP-A 2004-339319 (KOKAI)).
However, the blue-light-emitting element for use in white-light-emitting semiconductor devices emits near ultraviolet rays besides blue light, and there have hence been the following problems. That part of the epoxy-resin encapsulating material which is located near the blue-light-emitting element yellows, or the encapsulating material is thermally deteriorated by the heat emitted by the blue-light emitting element. In applications where high brightness is required, such as electric lamps, the quantity of light emitted by the blue-light-emitting element is large and yellowing and thermal deterioration have been apt to occur.
Because of this, investigations have been made on silicone-resin encapsulating materials as an encapsulating material which is not yellowed by near ultraviolet rays even when placed in a high-brightness environment and has heat resistance. However, a silicone resin formed from dimethylsiloxane has poor adhesion to light-emitting elements and substrates. Furthermore, this silicone resin has tackiness and, hence, dust particles and other substances are apt to adhere thereto. In addition, there have been cases where the carbon-carbon bonds formed during crosslinking are cleaved by near ultraviolet rays to impair the performance of the encapsulating material.
On the other hand, a polysiloxane film formed by the hydrolysis/condensation of an alkoxysilane monomer is apt to crack when thick, and has hence been undesirable for use as an encapsulating material for light-emitting elements.